Multi-speed transmission

ABSTRACT

A transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices may include clutches.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 11/950,463 filed on Dec. 5, 2007, which claims the benefit ofU.S. provisional Application No. 60/916,439 filed on May 7, 2007. Thedisclosures of the above applications are incorporated herein byreference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission havingeight or more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches, planetary gear arrangements and fixed interconnections toachieve a plurality of gear ratios. The number and physical arrangementof the planetary gear sets, generally, are dictated by packaging, costand desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,four planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices are for example clutches.

An embodiment of the transmission includes an input member, an outputmember, and first, second, third and fourth planetary gear sets eachhaving first, second and third members. A first interconnecting membercontinuously interconnects the third member of the first planetary gearset with the third member of the second planetary gear set. A secondinterconnecting member continuously interconnects the second member ofthe second planetary gear set with a stationary element. A thirdinterconnecting member continuously interconnects the second member ofthe second planetary gear set with the first member of the firstplanetary gear set. A fourth interconnecting member continuouslyinterconnects the first member of the third planetary gear set with thefirst member of the fourth planetary gear set. Five torque-transmittingmechanisms are selectively engageable to interconnect one of the first,second, and third members with another of the first, second, and thirdmembers. The torque-transmitting mechanisms are selectively engageablein combinations of at least three to establish at least eight forwardspeed ratios and at least one reverse speed ratio between the inputmember and the output member.

In one aspect of the embodiment of the present invention, a first of thefive torque transmitting mechanisms is selectively engageable tointerconnect the input member with the first member of the secondplanetary gear set.

In another aspect of the embodiment of the present invention, a secondof the five torque transmitting mechanisms is selectively engageable tointerconnect the third member of the first planetary gear set with thethird member of the fourth planetary gear set.

In yet another aspect of the embodiment of the present invention, athird of the five torque transmitting mechanisms is selectivelyengageable to interconnect the second member of the first planetary gearset with the third member of the fourth planetary gear set.

In yet another aspect of the embodiment of the present invention, afourth of the five torque transmitting mechanisms is selectivelyengageable to interconnect the third member of the first planetary gearset with the second member of the fourth planetary gear set.

In yet another aspect of the embodiment of the present invention, afifth of the five torque transmitting mechanisms is selectivelyengageable to interconnect the second member of the fourth planetarygear set with the third member of the third planetary gear set.

In yet another aspect of the embodiment of the present invention, theinput member is continuously interconnected with the second member ofthe third planetary gear set and the output member is continuouslyinterconnected with the third member of the third planetary gear set.

In yet another aspect of the embodiment of the present invention, thefive torque transmitting mechanisms are clutches.

In yet another aspect of the embodiment of the present invention, thefirst members are sun gears, the second members are carrier members, andthe third members are ring gears.

Another embodiment of the transmission of the present invention includesan input member, an output member, first, second, third and fourthplanetary gear sets each having first, second and third members, whereinthe input member is continuously interconnected with the second memberof the third planetary gear set and the output member is continuouslyinterconnected with the third member of the third planetary gear set. Afirst interconnecting member continuously interconnects the third memberof the first planetary gear set with the third member of the secondplanetary gear set. A second interconnecting member continuouslyinterconnects the second member of the second planetary gear set with astationary element. A third interconnecting member continuouslyinterconnects the second member of the second planetary gear set withthe first member of the first planetary gear set. A fourthinterconnecting member continuously interconnects the first member ofthe third planetary gear set with the first member of the fourthplanetary gear set. A first torque transmitting mechanism is selectivelyengageable to interconnect the input member with the first member of thesecond planetary gear set. A second torque transmitting mechanism isselectively engageable to interconnect the third member of the firstplanetary gear set with the third member of the fourth planetary gearset. A third torque transmitting mechanism is selectively engageable tointerconnect the second member of the first planetary gear set with thethird member of the fourth planetary gear set. A fourth torquetransmitting mechanism is selectively engageable to interconnect thethird member of the first planetary gear set with the second member ofthe fourth planetary gear set. A fifth torque transmitting mechanism isselectively engageable to interconnect the second member of the fourthplanetary gear set with the third member of the third planetary gearset. The torque-transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.

In one aspect of the embodiment of the present invention, the torquetransmitting mechanisms are clutches.

In another aspect of the embodiment of the present invention, the firstmembers are sun gears, the second members are carrier members, and thethird members are ring gears.

Another embodiment of the transmission of the present invention includesan input member, an output member, first, second, third and fourthplanetary gear sets each having a sun gear member, a carrier member, anda ring gear member, wherein the input member is continuouslyinterconnected with the carrier member of the third planetary gear setand the output member is continuously interconnected with the ring gearmember of the third planetary gear set. A first interconnecting membercontinuously interconnects the ring gear member of the first planetarygear set with the ring gear member of the second planetary gear set. Asecond interconnecting member continuously interconnects the carriermember of the second planetary gear set with a stationary element. Athird interconnecting member continuously interconnects the carriermember of the second planetary gear set with the sun gear member of thefirst planetary gear set. A fourth interconnecting member continuouslyinterconnects the sun gear member of the third planetary gear set withthe sun gear member of the fourth planetary gear set. A first torquetransmitting mechanism is selectively engageable to interconnect theinput member with the sun gear member of the second planetary gear set.A second torque transmitting mechanism is selectively engageable tointerconnect the ring gear member of the first planetary gear set withthe ring gear member of the fourth planetary gear set. A third torquetransmitting mechanism is selectively engageable to interconnect thecarrier member of the first planetary gear set with the ring gear memberof the fourth planetary gear set. A fourth torque transmitting mechanismis selectively engageable to interconnect the ring gear member of thefirst planetary gear set with the carrier member of the fourth planetarygear set. A fifth torque transmitting mechanism is selectivelyengageable to interconnect the carrier member of the fourth planetarygear set with the ring gear member of the third planetary gear set. Thetorque-transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of an eight speedtransmission according to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of an eight speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting clutches in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that in the particular exampleprovided, the eight speed automatic transmission of the presentinvention has an arrangement of permanent mechanical connections betweenthe elements of the four planetary gear sets. A first component orelement of a first planetary gear set is permanently coupled to aground. A first component or element of a second planetary gear set isalso permanently coupled to a ground. A second component or element ofthe first planetary gear set is permanently coupled to a secondcomponent or element of the second planetary gear set. Finally, a secondcomponent or element of the third planetary gear set is permanentlycoupled to a second component or element of a fourth planetary gear set.

Referring now to FIG. 1, an embodiment of an eight speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear set are each represented by a node. Therefore, a single levercontains three nodes: one for the sun gear, one for the planet gearcarrier, and one for the ring gear. The relative length between thenodes of each lever can be used to represent the ring-to-sun ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines and torque transmitting mechanisms or devicessuch as clutches and brakes are presented as interleaved fingers. If thedevice is a brake, one set of the fingers is grounded. Furtherexplanation of the format, purpose and use of lever diagrams can befound in SAE Paper 810102, “The Lever Analogy: A New Tool inTransmission Analysis” by Benford and Leising which is hereby fullyincorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a fourth planetary gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C and an output shaft or member 22.

The input member 12 is coupled to the third node 18C of the thirdplanetary gear set 18. The output member 22 is coupled to the first node18A of the third planetary gear set 18. The first node 14A of the firstplanetary gear set 14 is coupled to a ground or transmission housing 40.The first node 16A of the second planetary gear set 16 is also coupledto the ground or transmission housing 40. The second node 14B of thefirst planetary gear set 14 is coupled to the second node 16B of thesecond planetary gear set 16. The second node 18B of the third planetarygear set 18 is coupled to the second node 20B of the fourth planetarygear set 20.

A first clutch 26 selectively connects the input member 12 to the thirdnode 16C of the second planetary gear set 16. A second clutch 28selectively connects the second node 14B of the first planetary gear set14 to the first node 20A of the fourth planetary gear set 20. A thirdclutch 30 selectively connects the second node 14B of the firstplanetary gear set 14 to the third node 20C of the fourth planetary gearset 20. A fourth clutch 32 selectively connects the third node 14C ofthe first planetary gear set 14 to the third node 20C of the fourthplanetary gear set 20. A fifth clutch 34 selectively connects the firstnode 20A of the fourth planetary gear set 20 to the first node 18A ofthe third planetary gear set 18.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the eight speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches and couplings are correspondinglypresented whereas the nodes of the planetary gear sets now appear ascomponents of planetary gear sets such as sun gears, ring gears, planetgears and planet gear carriers.

For example, the planetary gear set 14 is a planetary gear set thatincludes a sun gear member 14A, a planet gear carrier member 14C and aring gear member 14B. The sun gear member 14A is connected for commonrotation with a first shaft or interconnecting member 42. The ring gearmember 14B is connected to a second shaft or interconnecting member 44and to a third shaft or interconnecting member 46. The planet gearcarrier member 14C rotatably supports a set of planet gears 14D (onlyone shown) and is connected for common rotation with a fourth shaft orinterconnecting member 48. The planet gears 14D are configured tointermesh with the sun gear member 14A and the ring gear member 14B.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 22 is continuously connected with the final drive unitor transfer case (not shown).

The planetary gear set 16 is a planetary gear set that includes a sungear member 16C, a planet carrier member 16A that rotatably supports aset of planet gears 16D and a ring gear member 16B. The sun gear member16C is connected for common rotation with the first clutch 26. Theplanet carrier member 16A is connected to the ground or transmissionhousing 40 by a fifth shaft or interconnecting member 50 in order torestrict the planet carrier member 16A from rotating relative to theground or transmission housing 40. The planet carrier member 16A is alsoconnected for common rotation with the first interconnecting member 42.The ring gear member 16B is connected for common rotation with thesecond interconnecting member 44. The planet gears 16D are configured tointermesh with both the sun gear member 16C and the ring gear member16B.

The planetary gear set 18 is a planetary gear set that includes a sungear member 18B, a ring gear member 18A and a planet carrier member 18Cthat rotatably supports a set of planet gears 18D. The sun gear member18B is connected for common rotation with a sixth shaft orinterconnecting member 52. The ring gear member 18A is connected forcommon rotation with a seventh shaft or interconnecting member 54 andwith the output member 22. The planet carrier member 18C is connectedfor common rotation with the input member 12. The planet gears 18D areconfigured to intermesh with both sun gear member 18B and ring gearmember 18A.

The planetary gear set 20 is a planetary gear set that includes a sungear member 20B, a ring gear member 20C and a planet carrier member 20Athat rotatably supports a set of planet gears 20D. The sun gear member20B is connected for common rotation with the sixth interconnectingmember 52. The ring gear member 20C is connected for common rotationwith an eighth shaft or interconnecting member 56. The planet carriermember 20A is connected for common rotation with a ninth shaft orinterconnecting member 58. The planet gears 20D are configured tointermesh with both the sun gear member 20B and the ring gear member20C.

The torque-transmitting mechanisms or clutches 26, 28, 30, 32 and 34allow for selective interconnection of the shafts or interconnectingmembers, members of the planetary gear sets and the housing. Forexample, the first clutch 26 is selectively engageable to connect thesun gear member 16C to the input member 12. The second clutch 28 isselectively engageable to connect the third interconnecting member 46 tothe ninth interconnecting member 58. The third clutch 30 is selectivelyengageable to connect the third interconnecting member 46 to the eighthinterconnecting member 56. The fourth clutch 32 is selectivelyengageable to connect the fourth interconnecting member 48 to the eighthinterconnecting member 56. The fifth clutch 34 is selectively engageableto connect the seventh interconnecting member 54 to the ninthinterconnecting member 58.

Referring now to FIGS. 2 and 3, the operation of the embodiment of theeight speed transmission 10 will be described. It will be appreciatedthat transmission 10 is capable of transmitting torque from the inputshaft or member 12 to the output shaft or member 22 in at least eightforward speed or torque ratios and at least one reverse speed or torqueratio. Each forward and reverse speed or torque ratio is attained byengagement of one or more of the torque-transmitting mechanisms (i.e.first clutch 26, second clutch 28, third clutch 30, fourth clutch 32,and fifth clutch 34), as will be explained below. FIG. 3 is a truthtable presenting the various combinations of torque-transmittingmechanisms that are activated or engaged to achieve the various gearstates. Actual numerical gear ratios of the various gear states are alsopresented although it should be appreciated that these numerical valuesare exemplary only and that they may be adjusted over significant rangesto accommodate various applications and operational criteria of thetransmission 10. An example of the gear ratios that may be obtainedusing the embodiments of the present invention are also shown in FIG. 3.Of course, other gear ratios are achievable depending on the geardiameter, gear teeth count and gear configuration selected.

To establish reverse gear, the first clutch 26, the second clutch 28,and the fifth clutch 34 are engaged or activated. The first clutch 26connects the second sun gear member 16C to the input member 12. Thesecond clutch 28 connects the third interconnecting member 46 to theninth interconnecting member 58. The fifth clutch 34 connects theseventh interconnecting member 54 to the ninth interconnecting member58. Likewise, the eight forward ratios are achieved through differentcombinations of clutch engagement, as shown in FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the eight speed transmission 10 assumes, first of all,that all the clutches not specifically referenced in a given gear stateare inactive or disengaged and, second of all, that during gear shifts,i.e., changes of gear state, between at least adjacent gear states, aclutch engaged or activated in both gear states will remain engaged oractivated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third, and fourth planetary gear sets each having first, second,and third members; a first torque transmitting mechanism selectivelyengageable to interconnect the input member with the first member of thesecond planetary gear set; a second torque transmitting mechanismselectively engageable to interconnect the third member of the fourthplanetary gear set with at least one of the third member of the firstplanetary gear set and the third member of the second planetary gearset; a third torque transmitting mechanism selectively engageable tointerconnect the second member of the first planetary gear set with thethird member of the fourth planetary gear set; a fourth torquetransmitting mechanism selectively engageable to interconnect the secondmember of the fourth planetary gear set with at least one of the thirdmember of the first planetary gear set and the third member of thesecond planetary gear set; and a fifth torque transmitting mechanismselectively engageable to interconnect the second member of the fourthplanetary gear set with the third member of the third planetary gearset, and wherein a plurality of combinations of two torque-transmittingmechanisms are disengaged to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 2. The transmission of claim 1 wherein one of the atleast one reverse speed ratios is achieved by engagement of the first,fourth, and fifth torque transmitting mechanisms.
 3. The transmission ofclaim 2 wherein a first of the at least eight forward speed ratios isachieved by engagement of the first, second, and fifth torquetransmitting mechanisms.
 4. The transmission of claim 3 wherein a secondof the at least eight forward speed ratios is achieved by engagement ofthe first, third, and fifth torque transmitting mechanisms.
 5. Thetransmission of claim 4 wherein a third of the at least eight forwardspeed ratios is achieved by engagement of the second, third, and fifthtorque transmitting mechanisms.
 6. The transmission of claim 5 wherein afourth of the at least eight forward speed ratios is achieved byengagement of the third, fourth, and fifth torque transmittingmechanisms.
 7. The transmission of claim 6 wherein a fifth of the atleast eight forward speed ratios is achieved by engagement of thesecond, fourth, and fifth torque transmitting mechanisms.
 8. Thetransmission of claim 7 wherein a sixth of the at least eight forwardspeed ratios is achieved by engagement of the second, third, and fourthtorque transmitting mechanisms.
 9. The transmission of claim 8 wherein aseventh of the at least eight forward speed ratios is achieved byengagement of the first, second, and fourth torque transmittingmechanisms.
 10. The transmission of claim 9 wherein an eighth of the atleast eight forward speed ratios is achieved by engagement of the first,third, and fourth torque transmitting mechanisms.
 11. The transmissionof claim 1 wherein the third member of the first planetary gear set iscontinuously interconnected with the third member of the secondplanetary gear set, the second member of the second planetary gear setis continuously interconnected with a stationary element, the secondmember of the second planetary gear set is continuously interconnectedwith the first member of the first planetary gear set, and the firstmember of the third planetary gear set is continuously interconnectedwith the first member of the fourth planetary gear set.
 12. Thetransmission of claim 1 wherein the first members are sun gears, thesecond members are carrier members, and the third members are ringgears.
 13. The transmission of claim 1 wherein each of the torquetransmitting mechanisms is engaged in at least five of the speed ratios.14. A transmission comprising: an input member; an output member; first,second, third, and fourth planetary gear sets each having sun, carrier,and ring members; at least four continuous interconnections from atleast one of the sun members, the carrier members, the ring members, anda stationary member to at least one other of the sun, carrier, and ringmembers; a first torque transmitting mechanism selectively engageable tointerconnect the input member with the sun member of the secondplanetary gear set; a second torque transmitting mechanism selectivelyengageable to interconnect the ring member of the fourth planetary gearset with at least one of the ring member of the first planetary gear setand the ring member of the second planetary gear set; a third torquetransmitting mechanism selectively engageable to interconnect thecarrier member of the first planetary gear set with the ring member ofthe fourth planetary gear set; a fourth torque transmitting mechanismselectively engageable to interconnect the carrier member of the fourthplanetary gear set with at least one of the ring member of the firstplanetary gear set and the ring member of the second planetary gear set;and a fifth torque transmitting mechanism selectively engageable tointerconnect the carrier member of the fourth planetary gear set withthe ring member of the third planetary gear set, and wherein a pluralityof combinations of at least three engaged torque-transmitting mechanismsand at least two disengaged torque-transmitting mechanisms establish atleast eight forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.
 15. The transmission ofclaim 14 wherein the first torque transmitting mechanism is engaged inat least a first, second, seventh, and eighth of the at least eightforward speed ratios and at least one of the at least one reverse speedratio.
 16. The transmission of claim 14 wherein the second torquetransmitting mechanism is engaged in at least a first, third, fifth,sixth, and seventh of the at least eight forward speed ratios.
 17. Thetransmission of claim 14 wherein the third torque transmitting mechanismis engaged in at least a second, third, fourth, sixth, and eighth of theat least eight forward speed ratios.
 18. The transmission of claim 14wherein the fourth torque transmitting mechanism is engaged in at leasta fourth, fifth, sixth, seventh, and eighth of the at least eightforward speed ratios and at least one of the at least one reverse speedratio.
 19. The transmission of claim 14 wherein the fifth torquetransmitting mechanism is engaged in at least a first, second, third,fourth, and fifth of the at least eight forward speed ratios and atleast one of the at least one reverse speed ratio.
 20. A transmissioncomprising: an input member; an output member; first, second, third, andfourth planetary gear sets each having first, second, and third members,wherein the input member is interconnected with the second member of thethird planetary gear set and the output member is interconnected withthe third member of the third planetary gear set; a selectively engagedreverse torque transfer path including the first member of the secondplanetary gear set interconnected with the input member and the thirdmembers of the first and second planetary gear sets interconnected withthe second member of the fourth planetary gear set and the third memberof the third planetary gear set; a selectively engaged first torquetransfer path including the first member of the second planetary gearset interconnected with the input member, the third members of the firstand second planetary gear sets interconnected with the third member ofthe fourth planetary gear set, and the second member of the fourthplanetary gear set interconnected with the third member of the thirdplanetary gear set; a selectively engaged second torque transfer pathincluding the first member of the second planetary gear setinterconnected with the input member, the third member of the fourthplanetary gear set interconnected with the second member of the firstplanetary gear set, and the second member of the fourth planetary gearset interconnected with the third member of the third planetary gearset; a selectively engaged third torque transfer path including thethird members of the first and second planetary gear sets interconnectedwith the third member of the fourth planetary gear set and the secondmember of the first planetary gear set, and the second member of thefourth planetary gear set interconnected with third member of the thirdplanetary gear set; a selectively engaged fourth torque transfer pathincluding the third members of the first and second planetary gear setsinterconnected with the second member of the fourth planetary gear setand the third member of the third planetary gear set, and the secondmember of the first planetary gear set interconnected with the thirdmember of the fourth planetary gear set; a selectively engaged fifthtorque transfer path including the third members of the first and secondplanetary gear sets interconnected with the second member of the fourthplanetary gear set and the third member of the third and fourthplanetary gear sets; a selectively engaged sixth torque transfer pathincluding the third members of the first and second planetary gear setsinterconnected with the second member of the first planetary gear setand the second and third members of the fourth planetary gear set; aselectively engaged seventh torque transfer path including the firstmember of the second planetary gear set interconnected with the inputmember, and the third members of the first and second planetary gearsets interconnected with the second and third members of the fourthplanetary gear set; and a selectively engaged eighth torque transferpath including the first member of the second planetary gear setinterconnected with the input member, the second member of the firstplanetary gear set interconnected with the third member of the fourthplanetary gear set, and the third members of the first and secondplanetary gear sets interconnected with the second member of the fourthplanetary gear set.